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ASK THE EXPERT- MULTIPROTOCOL LABEL SWITCHING

Welcome to the Cisco Networking Professionals Ask the Expert conversation. This is an opportunity to discuss MPLS with Cisco expert Zaheer Aziz. Zaheer is a co-author of Cisco Press Book "Troubleshooting IP Routing Protocols". Zaheer currently works as a technical marketing engineer with emphasis on MPLS networks. Feel free to post any questions relating to MPLS. Remember to use the rating system to let Zaheer know if you’ve received an adequate response.

Zaheer might not be able to answer each question due to the volume expected during this event. Our moderators will post many of the unanswered questions in other discussion forums shortly after the event. This event lasts through January 17. Visit this forum often to view responses to your questions and the questions of other community members.

37 REPLIES
Bronze

Re: ASK THE EXPERT- MULTIPROTOCOL LABEL SWITCHING

I've been wanting to learn about MPLS, as I currently know basically nothing about it. Could you start off with an overview of what problem(s) MPLS was created to solve? Are these problems just as relevant today as they were when work on MPLS first began? Primarily, I'm wondering is what types of networks can benefit from MPLS. For example, Sprint says that their backbone is designed so well that it doesn't need MPLS, yet we know that other Tier-1's are using it. The suggestion here seems to be that MPLS can only help networks that aren't designed optimally. Is this the case?

Thanks,

Terry

Community Member

Re: ASK THE EXPERT- MULTIPROTOCOL LABEL SWITCHING

Tery,

MPLS was designed basically to provide optimal use of your links. In my opinion MPLS without TE (traffic engineeing) is nothing. So if one needs to implement MPLS they should implement traffic engineering along with it.

Another advantage of MPLS is that no more layer 3 routing table lookup, instead label will be assigned to IP address and those label will be used instead IP prefixs.

Now most of the Tier 1's are using TE for proper use of bandwidth.

hope this helps:)

javed

Community Member

Re: ASK THE EXPERT- MULTIPROTOCOL LABEL SWITCHING

There are multiple problems that MPLS can solve(or do it in a different way)

that traditional IP forwarding was doing.

Example

1)To seperate data plane(Packet forwarding) from control place(IP protocols).

This gives the advantage in MPLS-VPN where overlapping address schemes

in customer VPN can be carried across shared MPLS backbone. This is just

one example

2)MPLS-TE. To effectively use unutilize links in the network. In addition to do unequal

cost load balancing which no IP routing protocol can achieve other than EIGRP

3)L2-VPN. To connect customer lans and offices via Internet and shared infrastructure.

These are some of the benefits and by all means not all of them. Hope this would be good start. Take a looks Cisco Networkers presentations on Value added services that MPLS can offer

Thanks

Zaheer Aziz(ASK the expert host)

Community Member

Re: ASK THE EXPERT- MULTIPROTOCOL LABEL SWITCHING

Hi all,

We want to enable MPLS VPNs to our network. Having several switches (i.e 65xx,4xxx,29xx) is not clear enough if they all support 'jumbo' frames (>1504), especially 2948G's and 2948G-L3's.

Is there a summary-link (regarding MTU-related problems) posted ?

Community Member

Re: ASK THE EXPERT- MULTIPROTOCOL LABEL SWITCHING

HI,

Jumbo frames are supported on the CAT 6K in 6.1(1) and 12.1(1)E but are dependent on the line cards being used. Pls check the following url:

http://www.cisco.com/warp/public/473/148.html

as far as 2900 is concerned u may want to check 2900 configuration book there is way you can change the MTU size in 2900, i just don't remember top of my head.

javed

Community Member

Re: ASK THE EXPERT- MULTIPROTOCOL LABEL SWITCHING

What do you recommend in order to learn more about MPLS, it's capabilities and a good working understanding of the technology for implementation?

Community Member

Re: ASK THE EXPERT- MULTIPROTOCOL LABEL SWITCHING

HI,

To learn and understand more about MPLS, i will say check out book written by Yakov and Bruce called " MPLS".

also to know more about the implementation and capabilities, following url will give you great information.

http://www.mplsrc.com/

javed

Community Member

Re: ASK THE EXPERT- MULTIPROTOCOL LABEL SWITCHING

Thanks for the link - it is extremely helpful.

Community Member

Re: ASK THE EXPERT- MULTIPROTOCOL LABEL SWITCHING

Hi,

I'd like to know about MPLS Cisco's solution supported protocols:

- what are the protocols used for the traffic engineering?

- for MPLS layer 2 VPNs which is the effective signaling protocol supported by Cisco's routers. (Martini, Kompella...)

- Is possible to implement Layer 2 VPN with different media type ad the end of the MPLS cloud?

Thx,

Graziano

Community Member

Re: ASK THE EXPERT- MULTIPROTOCOL LABEL SWITCHING

HI,

Cisco uses RSVP protocol for TE.

javed

Community Member

Re: ASK THE EXPERT- MULTIPROTOCOL LABEL SWITCHING

-TE uses RSVP as a label distribution protocol and for resource reservation.

TE also need Link State IP protocol it uses IS-IS and OSPF to do that.

http://www.cisco.com/en/US/partner/products/sw/iosswrel

/ps1834/products_feature_guide09186a008008029b.html

may be a good start.

You can also read book written by Eric Osborne and Ajay Simha. Search with their name

-Cisco Router uses Martini signalling with LDP

Community Member

Re: ASK THE EXPERT- MULTIPROTOCOL LABEL SWITCHING

Hi,

Thanks for the answers, I've other question:

With L2VPN Martini draft, is possible connect two different layer two media type? eg: have a L2VPN between a Frame relay VC and ATM VC

If Cisco use LDP signalling protocol for L2VPN, What is the signalling protocol for L3VPN, M-BGP or LDP?

Thanks a lot

Bye,

Graz.

Community Member

Re: ASK THE EXPERT- MULTIPROTOCOL LABEL SWITCHING

1)Any to Any connectivity is what is referred to what you are saying.

AFAIK Cisco is working on this functionality but I dont have the dates.

2)In L2-VPN you need psudo wire between PE and LDP is used there.

In L3-VPN, you need a LSP(label switch path) between PE achieved via LDP/TDP/RSVP (if TE is deployed). MP-BGP is used to carry VPN routes across MPLS backbone.

Hope this helps

Zaheer

Community Member

Re: ASK THE EXPERT- MULTIPROTOCOL LABEL SWITCHING

Hi,

- Is there L-LSP implementation of Cisco? May MPLS Class of ServiceCan (cell mode I mean) be considered as L-LSP or it is a modified E-LSP?

- When cisco will implement policy routing on a vrf interface to forward vpn traffic to a TE Tunnel on the PE itself? It can be used for all delay sensitive traffic from different VRFs so that all such traffic follows through a special TE Tunnel but all other data flows forwarding table or onother Te Tunnel. Is there any method doing this exactly? ( Diff-ser Aware TE doesn't do exactly what I mean)

- Is there any plan to implement ATOM support into every type of router above 2600?

Best Regards

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